The present invention is generally directed toward thread forming taps and, more particularly, to a new and improved thread forming tap for use in providing a locking thread form on the interior of a suitable aperture, bore, etc. Toward this end, the tap of the present invention is adapted to form a thread within such a bore having a flat area or ramp located at the thread root. The ramp is located or oriented at a preselected angle relative to the axis of the bore and the particular angle of such ramp is designed so as to allow the threads to be manufactured to normal commercial tolerances and assure that positive contact is made with the crown or crest of the mating thread of the male threaded element inserted into the bore, whereby to positively prevent loosening of the male member relative to the bore under vibrational or other adverse conditions. The angle of the ramp formed on the thread of the tap, and hence the angle of the complementary ramp formed by the tap in a bore may be varied in accordance with the degree of harness of the workpiece in order to achieve optimum locking characteristics. The tap is designed such that the inclined ramp thereof permits free running of the male threaded member relative to the tapped bore until such time as the degree of loading on the male member and workpiece in which the tapped bore is formed reach a predetermined magnitude, whereby the thread crown of the male member moves into contact with the ramp of the threaded bore in the workpiece. Complete tightening of the male threaded member onto the workpiece results in substantially full engagement of the respective thread faces which occurs, for example, in the case of an one-half inch diameter bolt, is subjected to a 90 foot-pound load.
It is accordingly a general object of the present invention to provide a new and improved tap for providing a locking thread form in a suitable aperture, bore, etc.
It is a more particular object of the present invention to provide a tap for forming threads on a female threaded member wherein the threads are provided with an inclined ramp adapted to lockingly engage the crest of the threads of the associated male threaded member such as a screw, bolt or the like.
It is still another object of the present invention to provide a new and improved tap of the above-described type which may be utilized to form threads of optimum locking characteristics commensurate with the material of the workpieces in which the threads are to be formed
Other objects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.